In the field of production of various electronic devices represented by semiconductor devices which must be microfabricated in the order of quarter microns, devices with higher density and integration are increasingly demanded to be produced. Accordingly, photolithographic technologies for forming a micropattern are facing more and more severe demands.
Particularly, in production of DRAMs having an integration degree of 1 G bits or more which requires a processing technology in the order of 0.13 micrometers or less, photolithography with an ArF excimer laser (193 nm) is anticipated to be used.
Recently, use of photolithography with an F2 excimer laser (157 nm) has been examined for forming a more minute pattern (see R. R. Kunz et al., Journal of Vacuum Science and Technology, Vol. B17 (No. 6), pp. 3267-3272 (1999)).
Thus, a resist material applicable to photolithography using F2 excimer laser light has been desired to be developed. Development of the resist for F2 exposure must improve cost performance of the laser, since a gas as a material for the laser has a short life, laser equipment itself is expensive, etc. Specifically, the resist is highly demanded to have high sensitivity, in addition to high resolution corresponding to a reduction in the processing size.
A chemically amplified resist is known well, in which a photoacid generator as a sensitizer is used as means for providing the resist with high sensitivity. This resist is now widely used as a resist for a KrF excimer laser (248 nm) and a resist for an ArF excimer laser. A feature of the chemically amplified resist is that proton acid, generated by irradiation with light from a photoacid generator as a component contained in the resist, causes an acid catalyst reaction with the resist resin or the like by heating treatment after exposure. In this manner, the resist has sensitivity remarkably higher than a conventional resist with a photoreaction efficiency (reaction per photon) of less than 1. Now, most of the resists developed are chemically amplified resists.
However, in the case of photolithography using light at a short wavelength of 190 nm or less typified by F2 excimer laser light, a resist for forming a micropattern is required to have a new characteristic that cannot be accomplished by a conventional material, specifically, high transparency to exposure light at 190 nm or less.
A conventional photoresist material for a KrF excimer laser or ArF excimer laser mainly employs poly(p-vinylphenol), an alicyclic resin or the like as a resin component. However, such a resin extremely highly absorbs light at a wavelength of 190 nm or less. Thus, since most of the exposure light is absorbed on the surface of the resist and is not transmitted to the substrate, a fine resist pattern cannot be formed. This is why such a conventional resin cannot be applied to photolithography using light at a short wavelength of 190 nm or less as is.
As a polymer compound transparent to F2 excimer laser light (157 nm), a resin containing a fluorine atom is assumed to be promising (see R. R. Kunz et al., Journal of Vacuum Science and Technology, Vol. B17 (No. 6), pp. 3267-3272 (1999) and T. Chiba et al., Journal of Photopolymer Science and Technology, Vol. 13 (No. 4), pp. 657-664 (2000)).